The invention relates to improvements in methods of and in apparatus for making so-called all-thread bobbins. More particularly, the invention relates to improvements in methods of and in apparatus for automatically winding all-thread bobbins for use in sewing machines or for other purposes. Still more particularly, the invention relates to improvements in methods of and in apparatus for making all-thread bobbins of the class disclosed, for example, in German Pat. No. 287 111 granted Jun. 3, 1914 to Levy for a winding machine for the making of disc-shaped bobbins for use in sewing and knitting machines.
The lower thread or underthread for the making of seams in a sewing machine is normally stored on a reel which is removably confined in a gripper housing or casing. During each of a series of stitch formations, the housing or casing is once surrounded by a looped portion of the upper thread which passes through the eye of the needle in the sewing machine. The space which is available in the sewing machine for the aforementioned housing or casing containing a supply of convoluted underthread is very limited, and additional space is taken up by the housing or casing as well as by the reel which actually stores the supply of convoluted underthread. The reel is normally made of a metallic or plastic material and often includes a central core between two disc-shaped flanges. The supply of convoluted underthread is wound around the core in the space between the two flanges.
Another drawback of reels for supplies of underthread is that, when the convoluted thread is to be drawn off the reel, the reel must be accelerated from zero speed. The inertia to be overcome during each acceleration of the reel is quite pronounced, especially when the reel still contains a full supply or a relatively large supply of convoluted underthread. The result is a continuous variation of tension upon the thread and the making of nonuniform stitches.
The aforementioned German Pat. No. 287 111 to Levy discloses a winding machine which is to turn out disc-shaped bobbins consisting entirely of convoluted thread or yarn. The winding operation involves the utilization of a large-diameter winding shaft between two flanges having axial passages for the axially reciprocable and rotatable winding shaft. When the making of a bobbin is completed, the shaft is withdrawn from the space between the flanges, i.e., from the center of the freshly formed bobbin, and leaves therein a relatively large axially extending hole. During the making of a bobbin between the flanges, the rotating shaft draws thread from a source of supply and through a thread guide. The latter is designed in such a way that, when a fully grown bobbin is evacuated from the space between the flanges upon extraction of the shaft from such space, a portion of the thread is placed in front of a specially configurated (crown-shaped) end portion of the shaft so that the shaft engages and begins to wind the thread as soon as it is returned to the winding position in which it extends across the space between the two flanges. The thread is thereupon severed between the shaft and the evacuated bobbin, and the thread guide is returned to its normal position preparatory to setting of the shaft in rotary motion in order to proceed with the winding of a fresh bobbin.
In addition to turning out bobbins having large-diameter holes, the machine of Levy exhibits the drawback that the thread guide must be capable of positioning a portion of the thread with a very high degree of accuracy, namely so that the thread crosses an extension of the longitudinal axis of the shaft; this should ensure that the end portion of the shaft will properly engage the thread preparatory to winding of a fresh bobbin. This is possible only by employing accurately finished, mounted and predictably manipulated thread guides as well as by employing means for reliably holding a fully grown bobbin in a predetermined position. If the fully grown bobbin is out of such predetermined position, the thread guide cannot engage the thread and cannot locate the thread in a requisite position relative to the end portion of the shaft. The end portion of the shaft is to force the properly positioned portion of the thread into a socket of one of the flanges; this can result in damage to or in actual tearing of the thread. Such damage to or tearing of the thread can create problems in connection with proper engagement of the guided thread portion with the end portion of the shaft. The diameter of the shaft cannot be reduced at will because the front end portion of the shaft must have dimensions which are sufficient to ensure proper engagement of the thread. In other words, it is necessary to provide each disc-shaped bobbin with a large-diameter hole at the expense of overall quantity of convoluted thread.
U.S. Pat. No. 1,598,262 (granted Aug. 21, 1926 to Ashworth for "Cop-Winding Machine") discloses an apparatus for converting thread into a cop which is merely a mass of thread and wherein the turns are held together by wax. The patentee is primarily concerned with a knock-off lever which is operable to move between two winding flanges in order to expel a completed cop upon extraction of the winding shaft.
French patent application Ser. No. 2,003,133 (filed by Plutte, Koecke & Co. for a thread winding apparatus and a bobbin which is obtainable by resorting to such apparatus and published Nov. 7, 1969) proposes an apparatus for the making of a cylindrical all-thread bobbin with a large axial hole. The applicant is concerned with a device which serves to strip a fully grown all-thread bobbin off a rotary winding spindle.
U.S. Pat. No. 1,688,058 (granted Oct. 16, 1928 to Reed for "Cop-winding Machine") discloses an apparatus for the making of flat disk-like cops from waxed thread. The winding shaft can be driven only when it assumes an operative position of engagement with a driving shaft. At such time, the driving shaft can turn the winding shaft by way of a torque transmitting clutch.
U.S. Pat. No. 2,780,191 (granted Feb. 5, 1957 to Philips for "Sewing machine bobbins of either silk, cotton, nylon or other fibres or synthetic material, and methods of making the same") discloses all-thread bobbins and a method of making such bobbins. A finished all-thread bobbin is heated to a temperature of substantially 300.degree. F. and is simultaneously subjected to a pressure of approximately 1000 pounds applied axially and radially for time periods varying according to the type of material being processed. This is intended to cause coherent setting of thread into a substantially solid and rigid cylindrical mass.
U.S. Pat. No. 2,815,178 (granted Dec. 3, 1957 to Cone for "Thread package winding apparatus") proposes to wind thread on plastic sewing machine bobbins. The mass of thread which is being wound upon a plastic bobbin is compacted by urging it into radial engagement with a winding spindle. A wound bobbin is doffed and the patented apparatus employs conveyor means for removing doffed bobbins as well as for supplying empty bobbins. The apparatus of Cone is designed to simultaneously wind thread onto a plurality of plastic bobbins.